Spin-selective thermoelectric properties and field-induced band engineering in bilayer zigzag silicene nanoribbons

Abstract

Silicene, a two-dimensional allotrope of silicon, has attracted significant attention due to its unique electronic properties and potential for diverse applications. Unlike its bulk counterpart, silicene exhibits remarkable quantum phenomena due to its low-dimensional structure and strong spin–orbit coupling. In this study, we investigate the spin and charge transport, as well as the thermoelectric properties, of zigzag bilayer silicene nanoribbons in nonmagnetic (NM), ferromagnetic (FM), and antiferromagnetic (AFM) configurations under perpendicular electric fields. The analysis is carried out using tight-binding and non-equilibrium Green’s function methods. Numerical simulations reveal that half-metallic behavior can be induced in the FM and AFM configurations by tuning the electric field. We demonstrate spin-resolved thermoelectric figures of merit reaching ZeTS = 1.85 (FM) and 1.2 (AFM), induced by electric-field-tuned half-metallicity and spin-dependent bandgaps. These enhancements are attributed to the electric-field-induced bandgap modulation and improved transport coefficients. The unique properties of silicene make it a promising candidate for applications in next-generation spintronic devices, such as spin transistors and magnetic memory storage technologies.